It is known to use a pair of planetary gear configurations to provide differential drive respectively to a pair of output assemblies such as ground engaging wheels or a continuous belt or track, wherein the planetary gear configurations are arranged such that their respective sun gears are driven by a common drive member or shaft. The main drive source, typically a drive shaft propelled by an internal combustion engine, may be in mesh with a ring gear of one of the planetary gear configurations to provide direcitionality and gear reduction. Typically, the drive source includes a rotational axis perpendicularly disposed relative to the rotational axis of a driven axle, here referred to as a cross drive.
Such cross drive connections causes losses in the power transfer. An electrically driven power train where the drive source has been integrated into the differential reduces these losses and provides a more compact power train assembly.
US 2003/0203782 discloses a differential assembly including an electrically operated input device, a first planetary assembly and a second planetary assembly. The first planetary is in driving engagement with the input device and the first planetary is drivingly connected to a first output assembly. The second planetary assembly is in driving engagement with the first planetary assembly and is drivingly connected to a second output assembly wherein the first planetary assembly co-acts with the second planetary assembly to provide substantially the same torque to the first and second output assemblies.
The differential assembly according to US 2003/0203782 provides a relatively compact solution with a reduction in losses between the drive source and the final drive assemblies, and limits wheel slippage. Although the differential assembly according to US 2003/0203782 gives a compact solution, space in e.g. vehicles becomes more and more important and thus there is a need to further increase compactness in order to save space. Further said differential assembly may have disadvantages regarding ability to brake the differential due to e.g. ware of rotating components during braking and disadvantages due to energy losses during differential brake and thus reduction in efficiency.